MQTTClient.h

00001 /*******************************************************************************
00002  * Copyright (c) 2014 IBM Corp.
00003  *
00004  * All rights reserved. This program and the accompanying materials
00005  * are made available under the terms of the Eclipse Public License v1.0
00006  * and Eclipse Distribution License v1.0 which accompany this distribution.
00007  *
00008  * The Eclipse Public License is available at
00009  *    http://www.eclipse.org/legal/epl-v10.html
00010  * and the Eclipse Distribution License is available at
00011  *   http://www.eclipse.org/org/documents/edl-v10.php.
00012  *
00013  * Contributors:
00014  *    Ian Craggs - initial API and implementation and/or initial documentation
00015  *******************************************************************************/
00016  
00017  /*
00018  
00019  TODO: 
00020  
00021  ensure publish packets are retried on reconnect
00022  
00023  updating usage of FP. Try to remove inclusion of FP.cpp in main. sg-
00024  
00025  */
00026 
00027 #if !defined(MQTTCLIENT_H)
00028 #define MQTTCLIENT_H
00029 
00030 #include "FP.h"
00031 #include "MQTTPacket.h"
00032 #include "stdio.h"
00033 
00034 namespace MQTT
00035 {
00036 
00037 
00038 enum QoS { QOS0, QOS1, QOS2 };
00039 
00040 enum returnCode { BUFFER_OVERFLOW = -2, FAILURE = -1, SUCCESS = 0 };
00041 
00042 
00043 struct Message
00044 {
00045     enum QoS qos;
00046     bool retained;
00047     bool dup;
00048     unsigned short id;
00049     void *payload;
00050     size_t payloadlen;
00051 };
00052 
00053 
00054 struct MessageData
00055 {
00056     struct Message message;
00057     char* topicName;
00058 };
00059 
00060 
00061 class PacketId
00062 {
00063 public:
00064     PacketId()
00065     {
00066         next = 0;
00067     }
00068     
00069     int getNext()
00070     {
00071         return next = (next == MAX_PACKET_ID) ? 1 : ++next;
00072     }
00073    
00074 private:
00075     static const int MAX_PACKET_ID = 65535;
00076     int next;
00077 };
00078   
00079   
00080 /**
00081  * @class Client
00082  * @brief blocking, non-threaded MQTT client API
00083  * 
00084  * This version of the API blocks on all method calls, until they are complete.  This means that only one
00085  * MQTT request can be in process at any one time.  
00086  * @param Network a network class which supports send, receive
00087  * @param Timer a timer class with the methods: 
00088  */ 
00089 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE = 100, int MAX_MESSAGE_HANDLERS = 5> class Client
00090 {
00091     
00092 public:
00093    
00094     typedef void (*messageHandler)(Message*);
00095 
00096     /** Construct the client
00097      *  @param network - pointer to an instance of the Network class - must be connected to the endpoint
00098      *      before calling MQTT connect
00099      *  @param limits an instance of the Limit class - to alter limits as required
00100      */
00101     Client(Network& network, unsigned int command_timeout_ms = 30000); 
00102     
00103     /** Set the default message handling callback - used for any message which does not match a subscription message handler
00104      *  @param mh - pointer to the callback function
00105      */
00106     void setDefaultMessageHandler(messageHandler mh)
00107     {
00108         defaultMessageHandler.attach(mh);
00109     }
00110     
00111     /** MQTT Connect - send an MQTT connect packet down the network and wait for a Connack
00112      *  The nework object must be connected to the network endpoint before calling this 
00113      *  @param options - connect options
00114      *  @return success code -  
00115      */       
00116     int connect(MQTTPacket_connectData* options = 0);
00117       
00118     /** MQTT Publish - send an MQTT publish packet and wait for all acks to complete for all QoSs
00119      *  @param topic - the topic to publish to
00120      *  @param message - the message to send
00121      *  @return success code -  
00122      */      
00123     int publish(const char* topicName, Message* message);
00124    
00125     /** MQTT Subscribe - send an MQTT subscribe packet and wait for the suback
00126      *  @param topicFilter - a topic pattern which can include wildcards
00127      *  @param qos - the MQTT QoS to subscribe at
00128      *  @param mh - the callback function to be invoked when a message is received for this subscription
00129      *  @return success code -  
00130      */   
00131     int subscribe(const char* topicFilter, enum QoS qos, messageHandler mh);
00132     
00133     /** MQTT Unsubscribe - send an MQTT unsubscribe packet and wait for the unsuback
00134      *  @param topicFilter - a topic pattern which can include wildcards
00135      *  @return success code -  
00136      */   
00137     int unsubscribe(const char* topicFilter);
00138     
00139     /** MQTT Disconnect - send an MQTT disconnect packet 
00140      *  @return success code -  
00141      */
00142     int disconnect();
00143     
00144     /** A call to this API must be made within the keepAlive interval to keep the MQTT connection alive
00145      *  yield can be called if no other MQTT operation is needed.  This will also allow messages to be 
00146      *  received.
00147      *  @param timeout_ms the time to wait, in milliseconds
00148      *  @return success code - on failure, this means the client has disconnected
00149      */
00150     int yield(int timeout_ms = 1000);
00151     
00152 private:
00153 
00154     int cycle(Timer& timer);
00155     int waitfor(int packet_type, Timer& timer);
00156     int keepalive();
00157 
00158     int decodePacket(int* value, int timeout);
00159     int readPacket(Timer& timer);
00160     int sendPacket(int length, Timer& timer);
00161     int deliverMessage(MQTTString& topicName, Message& message);
00162     bool isTopicMatched(char* topicFilter, MQTTString& topicName);
00163     
00164     Network& ipstack;
00165     unsigned int command_timeout_ms;
00166     
00167     char buf[MAX_MQTT_PACKET_SIZE];  
00168     char readbuf[MAX_MQTT_PACKET_SIZE];  
00169 
00170     Timer ping_timer;
00171     unsigned int keepAliveInterval;
00172     bool ping_outstanding;
00173     
00174     PacketId packetid;
00175     
00176     // typedef FP<void, Message*> messageHandlerFP;
00177     struct MessageHandlers
00178     {
00179         const char* topicFilter;
00180         //messageHandlerFP fp; typedefs not liked?
00181         FP<void, Message*> fp;
00182     } messageHandlers[MAX_MESSAGE_HANDLERS];      // Message handlers are indexed by subscription topic
00183     
00184     FP<void, Message*> defaultMessageHandler;
00185      
00186     bool isconnected;
00187 
00188 };
00189 
00190 }
00191 
00192 
00193 template<class Network, class Timer, int a, int MAX_MESSAGE_HANDLERS> 
00194 MQTT::Client<Network, Timer, a, MAX_MESSAGE_HANDLERS>::Client(Network& network, unsigned int command_timeout_ms)  : ipstack(network), packetid()
00195 {
00196     ping_timer = Timer();
00197     ping_outstanding = 0;
00198     for (int i = 0; i < MAX_MESSAGE_HANDLERS; ++i)
00199         messageHandlers[i].topicFilter = 0;
00200     this->command_timeout_ms = command_timeout_ms; 
00201     isconnected = false;
00202 }
00203 
00204 
00205 template<class Network, class Timer, int a, int b> 
00206 int MQTT::Client<Network, Timer, a, b>::sendPacket(int length, Timer& timer)
00207 {
00208     int rc = FAILURE, 
00209         sent = 0;
00210     
00211     while (sent < length && !timer.expired())
00212     {
00213         rc = ipstack.write(&buf[sent], length, timer.left_ms());
00214         if (rc < 0)  // there was an error writing the data
00215             break;
00216         sent += rc;
00217     }
00218     if (sent == length)
00219     {
00220         ping_timer.countdown(this->keepAliveInterval); // record the fact that we have successfully sent the packet    
00221         rc = SUCCESS;
00222     }
00223     else
00224         rc = FAILURE;
00225     return rc;
00226 }
00227 
00228 
00229 template<class Network, class Timer, int a, int b> 
00230 int MQTT::Client<Network, Timer, a, b>::decodePacket(int* value, int timeout)
00231 {
00232     char c;
00233     int multiplier = 1;
00234     int len = 0;
00235     const int MAX_NO_OF_REMAINING_LENGTH_BYTES = 4;
00236 
00237     *value = 0;
00238     do
00239     {
00240         int rc = MQTTPACKET_READ_ERROR;
00241 
00242         if (++len > MAX_NO_OF_REMAINING_LENGTH_BYTES)
00243         {
00244             rc = MQTTPACKET_READ_ERROR; /* bad data */
00245             goto exit;
00246         }
00247         rc = ipstack.read(&c, 1, timeout);
00248         if (rc != 1)
00249             goto exit;
00250         *value += (c & 127) * multiplier;
00251         multiplier *= 128;
00252     } while ((c & 128) != 0);
00253 exit:
00254     return len;
00255 }
00256 
00257 
00258 /**
00259  * If any read fails in this method, then we should disconnect from the network, as on reconnect
00260  * the packets can be retried. 
00261  * @param timeout the max time to wait for the packet read to complete, in milliseconds
00262  * @return the MQTT packet type, or -1 if none
00263  */
00264 template<class Network, class Timer, int a, int b> 
00265 int MQTT::Client<Network, Timer, a, b>::readPacket(Timer& timer) 
00266 {
00267     int rc = FAILURE;
00268     MQTTHeader header = {0};
00269     int len = 0;
00270     int rem_len = 0;
00271 
00272     /* 1. read the header byte.  This has the packet type in it */
00273     if (ipstack.read(readbuf, 1, timer.left_ms()) != 1)
00274         goto exit;
00275 
00276     len = 1;
00277     /* 2. read the remaining length.  This is variable in itself */
00278     decodePacket(&rem_len, timer.left_ms());
00279     len += MQTTPacket_encode(readbuf + 1, rem_len); /* put the original remaining length back into the buffer */
00280 
00281     /* 3. read the rest of the buffer using a callback to supply the rest of the data */
00282     if (ipstack.read(readbuf + len, rem_len, timer.left_ms()) != rem_len)
00283         goto exit;
00284 
00285     header.byte = readbuf[0];
00286     rc = header.bits.type;
00287 exit:
00288     return rc;
00289 }
00290 
00291 
00292 // assume topic filter and name is in correct format
00293 // # can only be at end
00294 // + and # can only be next to separator
00295 template<class Network, class Timer, int a, int b> 
00296 bool MQTT::Client<Network, Timer, a, b>::isTopicMatched(char* topicFilter, MQTTString& topicName)
00297 {
00298     char* curf = topicFilter;
00299     char* curn = topicName.lenstring.data;
00300     char* curn_end = curn + topicName.lenstring.len;
00301     
00302     while (*curf && curn < curn_end)
00303     {
00304         if (*curn == '/' && *curf != '/')
00305             break;
00306         if (*curf != '+' && *curf != '#' && *curf != *curn)
00307             break;
00308         if (*curf == '+')
00309         {   // skip until we meet the next separator, or end of string
00310             char* nextpos = curn + 1;
00311             while (nextpos < curn_end && *nextpos != '/')
00312                 nextpos = ++curn + 1;
00313         }
00314         else if (*curf == '#')
00315             curn = curn_end - 1;    // skip until end of string
00316         curf++;
00317         curn++;
00318     };
00319     
00320     return (curn == curn_end) && (*curf == '\0');
00321 }
00322 
00323 
00324 
00325 template<class Network, class Timer, int a, int MAX_MESSAGE_HANDLERS> 
00326 int MQTT::Client<Network, Timer, a, MAX_MESSAGE_HANDLERS>::deliverMessage(MQTTString& topicName, Message& message)
00327 {
00328     int rc = FAILURE;
00329 
00330     // we have to find the right message handler - indexed by topic
00331     for (int i = 0; i < MAX_MESSAGE_HANDLERS; ++i)
00332     {
00333         if (messageHandlers[i].topicFilter != 0 && (MQTTPacket_equals(&topicName, (char*)messageHandlers[i].topicFilter) ||
00334                 isTopicMatched((char*)messageHandlers[i].topicFilter, topicName)))
00335         {
00336             if (messageHandlers[i].fp.attached())
00337             {
00338                 messageHandlers[i].fp(&message);
00339                 rc = SUCCESS;
00340             }
00341         }
00342     }
00343     
00344     if (rc == FAILURE && defaultMessageHandler.attached()) 
00345     {
00346         defaultMessageHandler(&message);
00347         rc = SUCCESS;
00348     }   
00349     
00350     return rc;
00351 }
00352 
00353 
00354 
00355 template<class Network, class Timer, int a, int b> 
00356 int MQTT::Client<Network, Timer, a, b>::yield(int timeout_ms)
00357 {
00358     int rc = SUCCESS;
00359     Timer timer = Timer();
00360     
00361     timer.countdown_ms(timeout_ms);
00362     while (!timer.expired())
00363     {
00364         if (cycle(timer) == FAILURE)
00365         {
00366             rc = FAILURE;
00367             break;
00368         }
00369     }
00370         
00371     return rc;
00372 }
00373 
00374 
00375 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int b> 
00376 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::cycle(Timer& timer)
00377 {
00378     /* get one piece of work off the wire and one pass through */
00379 
00380     // read the socket, see what work is due
00381     int packet_type = readPacket(timer);
00382     
00383     int len = 0,
00384         rc = SUCCESS;
00385 
00386     switch (packet_type)
00387     {
00388         case CONNACK:
00389         case PUBACK:
00390         case SUBACK:
00391             break;
00392         case PUBLISH:
00393             MQTTString topicName;
00394             Message msg;
00395             if (MQTTDeserialize_publish((int*)&msg.dup, (int*)&msg.qos, (int*)&msg.retained, (int*)&msg.id, &topicName,
00396                                  (char**)&msg.payload, (int*)&msg.payloadlen, readbuf, MAX_MQTT_PACKET_SIZE) != 1)
00397                 goto exit;
00398             deliverMessage(topicName, msg);
00399             if (msg.qos != QOS0)
00400             {
00401                 if (msg.qos == QOS1)
00402                     len = MQTTSerialize_ack(buf, MAX_MQTT_PACKET_SIZE, PUBACK, 0, msg.id);
00403                 else if (msg.qos == QOS2)
00404                     len = MQTTSerialize_ack(buf, MAX_MQTT_PACKET_SIZE, PUBREC, 0, msg.id);
00405                 if (len <= 0)
00406                     rc = FAILURE;
00407                 else
00408                     rc = sendPacket(len, timer);
00409                 if (rc == FAILURE)
00410                     goto exit; // there was a problem
00411             }
00412             break;
00413         case PUBREC:
00414             int type, dup, mypacketid;
00415             if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, MAX_MQTT_PACKET_SIZE) != 1)
00416                 rc = FAILURE;
00417             else if ((len = MQTTSerialize_ack(buf, MAX_MQTT_PACKET_SIZE, PUBREL, 0, mypacketid)) <= 0)
00418                 rc = FAILURE;
00419             else if ((rc = sendPacket(len, timer)) != SUCCESS) // send the PUBREL packet
00420                 rc = FAILURE; // there was a problem
00421             if (rc == FAILURE)
00422                 goto exit; // there was a problem
00423             break;
00424         case PUBCOMP:
00425             break;
00426         case PINGRESP:
00427             ping_outstanding = false;
00428             break;
00429     }
00430     keepalive();
00431 exit:
00432     if (rc == SUCCESS)
00433         rc = packet_type;
00434     return rc;
00435 }
00436 
00437 
00438 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int b>
00439 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::keepalive()
00440 {
00441     int rc = FAILURE;
00442 
00443     if (keepAliveInterval == 0)
00444     {
00445         rc = SUCCESS;
00446         goto exit;
00447     }
00448 
00449     if (ping_timer.expired())
00450     {
00451         if (!ping_outstanding)
00452         {
00453             Timer timer = Timer(1000);
00454             int len = MQTTSerialize_pingreq(buf, MAX_MQTT_PACKET_SIZE);
00455             if (len > 0 && (rc = sendPacket(len, timer)) == SUCCESS) // send the ping packet
00456                 ping_outstanding = true;
00457         }
00458     }
00459 
00460 exit:
00461     return rc;
00462 }
00463 
00464 
00465 // only used in single-threaded mode where one command at a time is in process
00466 template<class Network, class Timer, int a, int b> 
00467 int MQTT::Client<Network, Timer, a, b>::waitfor(int packet_type, Timer& timer)
00468 {
00469     int rc = FAILURE;
00470     
00471     do
00472     {
00473         if (timer.expired()) 
00474             break; // we timed out
00475     }
00476     while ((rc = cycle(timer)) != packet_type);  
00477     
00478     return rc;
00479 }
00480 
00481 
00482 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int b> 
00483 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::connect(MQTTPacket_connectData* options)
00484 {
00485     Timer connect_timer = Timer(command_timeout_ms);
00486     int rc = FAILURE;
00487 
00488     MQTTPacket_connectData default_options = MQTTPacket_connectData_initializer;
00489     if (options == 0)
00490         options = &default_options; // set default options if none were supplied
00491     
00492     this->keepAliveInterval = options->keepAliveInterval;
00493     ping_timer.countdown(this->keepAliveInterval);
00494     int len = MQTTSerialize_connect(buf, MAX_MQTT_PACKET_SIZE, options);
00495     if (len <= 0)
00496         goto exit;
00497     if ((rc = sendPacket(len, connect_timer)) != SUCCESS)  // send the connect packet
00498         goto exit; // there was a problem
00499     
00500     // this will be a blocking call, wait for the connack
00501     if (waitfor(CONNACK, connect_timer) == CONNACK)
00502     {
00503         int connack_rc = -1;
00504         if (MQTTDeserialize_connack(&connack_rc, readbuf, MAX_MQTT_PACKET_SIZE) == 1)
00505             rc = connack_rc;
00506         else
00507             rc = FAILURE;
00508     }
00509     else
00510         rc = FAILURE;
00511     
00512 exit:
00513     if (rc == SUCCESS)
00514         isconnected = true;
00515     return rc;
00516 }
00517 
00518 
00519 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int MAX_MESSAGE_HANDLERS> 
00520 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, MAX_MESSAGE_HANDLERS>::subscribe(const char* topicFilter, enum QoS qos, messageHandler messageHandler)
00521 { 
00522     int rc = FAILURE;
00523     Timer timer = Timer(command_timeout_ms);
00524     int len = 0;
00525     
00526     MQTTString topic = {(char*)topicFilter, 0, 0};
00527     if (!isconnected)
00528         goto exit;
00529     
00530     len = MQTTSerialize_subscribe(buf, MAX_MQTT_PACKET_SIZE, 0, packetid.getNext(), 1, &topic, (int*)&qos);
00531     if (len <= 0)
00532         goto exit;
00533     if ((rc = sendPacket(len, timer)) != SUCCESS) // send the subscribe packet
00534         goto exit;             // there was a problem
00535     
00536     if (waitfor(SUBACK, timer) == SUBACK)      // wait for suback 
00537     {
00538         int count = 0, grantedQoS = -1, mypacketid;
00539         if (MQTTDeserialize_suback(&mypacketid, 1, &count, &grantedQoS, readbuf, MAX_MQTT_PACKET_SIZE) == 1)
00540             rc = grantedQoS; // 0, 1, 2 or 0x80 
00541         if (rc != 0x80)
00542         {
00543             for (int i = 0; i < MAX_MESSAGE_HANDLERS; ++i)
00544             {
00545                 if (messageHandlers[i].topicFilter == 0)
00546                 {
00547                     messageHandlers[i].topicFilter = topicFilter;
00548                     messageHandlers[i].fp.attach(messageHandler);
00549                     rc = 0;
00550                     break;
00551                 }
00552             }
00553         }
00554     }
00555     else 
00556         rc = FAILURE;
00557         
00558 exit:
00559     //if (rc == FAILURE)
00560     //   closesession();
00561     return rc;
00562 }
00563 
00564 
00565 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int MAX_MESSAGE_HANDLERS> 
00566 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, MAX_MESSAGE_HANDLERS>::unsubscribe(const char* topicFilter)
00567 {   
00568     int rc = FAILURE;
00569     Timer timer = Timer(command_timeout_ms);
00570     
00571     MQTTString topic = {(char*)topicFilter, 0, 0};
00572     
00573     int len = MQTTSerialize_unsubscribe(buf, MAX_MQTT_PACKET_SIZE, 0, packetid.getNext(), 1, &topic);
00574     if (len <= 0)
00575         goto exit;
00576     if ((rc = sendPacket(len, timer)) != SUCCESS) // send the subscribe packet
00577         goto exit; // there was a problem
00578     
00579     if (waitfor(UNSUBACK, timer) == UNSUBACK)
00580     {
00581         int mypacketid;  // should be the same as the packetid above
00582         if (MQTTDeserialize_unsuback(&mypacketid, readbuf, MAX_MQTT_PACKET_SIZE) == 1)
00583             rc = 0; 
00584     }
00585     else
00586         rc = FAILURE;
00587     
00588 exit:
00589     return rc;
00590 }
00591 
00592 
00593    
00594 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int b> 
00595 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::publish(const char* topicName, Message* message)
00596 {
00597     int rc = FAILURE;
00598     Timer timer = Timer(command_timeout_ms);
00599     
00600     MQTTString topicString = {(char*)topicName, 0, 0};
00601 
00602     if (message->qos == QOS1 || message->qos == QOS2)
00603         message->id = packetid.getNext();
00604     
00605     int len = MQTTSerialize_publish(buf, MAX_MQTT_PACKET_SIZE, 0, message->qos, message->retained, message->id, 
00606               topicString, (char*)message->payload, message->payloadlen);
00607     if (len <= 0)
00608         goto exit;
00609     if ((rc = sendPacket(len, timer)) != SUCCESS) // send the subscribe packet
00610         goto exit; // there was a problem
00611     
00612     if (message->qos == QOS1)
00613     {
00614         if (waitfor(PUBACK, timer) == PUBACK)
00615         {
00616             int type, dup, mypacketid;
00617             if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, MAX_MQTT_PACKET_SIZE) != 1)
00618                 rc = FAILURE;
00619         }
00620         else
00621             rc = FAILURE;
00622     }
00623     else if (message->qos == QOS2)
00624     {
00625         if (waitfor(PUBCOMP, timer) == PUBCOMP)
00626         {
00627             int type, dup, mypacketid;
00628             if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, MAX_MQTT_PACKET_SIZE) != 1)
00629                 rc = FAILURE;
00630         }
00631         else
00632             rc = FAILURE;
00633     }
00634     
00635 exit:
00636     return rc;
00637 }
00638 
00639 
00640 template<class Network, class Timer, int MAX_MQTT_PACKET_SIZE, int b> 
00641 int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::disconnect()
00642 {  
00643     int rc = FAILURE;
00644     Timer timer = Timer(command_timeout_ms);     // we might wait for incomplete incoming publishes to complete
00645     int len = MQTTSerialize_disconnect(buf, MAX_MQTT_PACKET_SIZE);
00646     if (len > 0)
00647         rc = sendPacket(len, timer);            // send the disconnect packet
00648 
00649     return rc;
00650 }
00651 
00652 
00653 #endif